Field
The present disclosure relates to gas oil separation plant (GOSP) technology. In particular, the disclosure relates to integrating crude oil desalting, dehydration, sweetening, and stabilization processes to create efficient GOSP systems and processes.
Description of Related Art
In general, a GOSP is a continuous separation process used to refine crude oil that includes a high pressure production trap (HPPT), a low pressure production trap (LPPT), a low pressure degassing tank (LPDT), a dehydrator unit, first and second stage desalting units, a water/oil separation plant (WOSEP), a stabilizer column, centrifugal pumps, heat exchangers, and reboilers. In a GOSP, the pressure is often reduced in several stages to allow the controlled separation of volatile components, such as entrained vapors. Goals of a GOSP include achieving maximum liquid recovery with stabilized oil separated from gas, and water separated from gases and oil. In other words, one purpose of a GOSP is to remove water, salt, and volatile hydrocarbon gases from wet crude oil after it is obtained from a hydrocarbon-bearing reservoir.
However, a large pressure reduction in a single separator will cause flash vaporization, leading to instability and safety hazards. Thus, in prior art GOSP's, many stages and units are required. FIG. 1 shows three stages in prior art GOSP systems and processes. In a first stage, gas, crude oil, and free water are separated. In a second stage, crude oil is dehydrated and desalted to separate emulsified water and salt to meet certain basic sediment and water (BSW) specifications. In a third stage, crude oil is stabilized and sweetened to meet hydrogen sulfide (H2S) and Reid Vapor Pressure (RVP) specifications.
GOSP's are oftentimes operated to meet the following specifications: (1) a salt concentration of not more than about 10 pound (lbs.) of salt/1000 barrels (PTB); (2) BSW content of not more than about 0.3 volume percent (V %); (3) H2S content (concentration) of less than about 60 ppm in either the crude stabilization tower (or degassing vessels in the case of sweet crude); and (4) a maximum RVP of about 7 pounds per square inch absolute (psia) and a maximum true vapor pressure (TVP) of about 13.5 psia at 130 degrees Fahrenheit (° F.). Certain characteristics of conventional GOSP systems and processes are described further with regard to FIG. 2.